altos/stm32l: Add support for software-driven HW flow control
[fw/altos] / src / stm / ao_serial_stm.c
index e7b6ab78d71acfa79b3724c0e8379825b337e312..bf07906016387c870213b0ae02316f0deb06b280 100644 (file)
@@ -16,6 +16,7 @@
  */
 
 #include <ao.h>
+#include <ao_exti.h>
 
 void
 ao_debug_out(char c)
@@ -29,40 +30,67 @@ ao_debug_out(char c)
 static int
 _ao_usart_tx_start(struct ao_stm_usart *usart)
 {
-       if (!ao_fifo_empty(usart->tx_fifo) && !usart->tx_started)
-       {
-               usart->tx_started = 1;
-               usart->tx_running = 1;
-               usart->reg->cr1 |= (1 << STM_USART_CR1_TXEIE) | (1 << STM_USART_CR1_TCIE);
-               ao_fifo_remove(usart->tx_fifo, usart->reg->dr);
-               ao_wakeup(&usart->tx_fifo);
-               return 1;
+       if (!ao_fifo_empty(usart->tx_fifo)) {
+#if HAS_SERIAL_SW_FLOW
+               if (usart->gpio_cts && ao_gpio_get(usart->gpio_cts, usart->pin_cts, foo) == 1) {
+                       ao_exti_enable(usart->gpio_cts, usart->pin_cts);
+                       return 0;
+               }
+#endif
+               if (usart->reg->sr & (1 << STM_USART_SR_TXE))
+               {
+                       usart->tx_running = 1;
+                       usart->reg->cr1 |= (1 << STM_USART_CR1_TXEIE) | (1 << STM_USART_CR1_TCIE);
+                       ao_fifo_remove(usart->tx_fifo, usart->reg->dr);
+                       ao_wakeup(&usart->tx_fifo);
+                       return 1;
+               }
        }
        return 0;
 }
 
+#if HAS_SERIAL_SW_FLOW
+static void
+_ao_usart_cts(struct ao_stm_usart *usart)
+{
+       if (_ao_usart_tx_start(usart))
+               ao_exti_disable(usart->gpio_cts, usart->pin_cts);
+}
+#endif
+
+static void
+_ao_usart_rx(struct ao_stm_usart *usart, int stdin)
+{
+       if (usart->reg->sr & (1 << STM_USART_SR_RXNE)) {
+               if (!ao_fifo_full(usart->rx_fifo)) {
+                       ao_fifo_insert(usart->rx_fifo, usart->reg->dr);
+                       ao_wakeup(&usart->rx_fifo);
+                       if (stdin)
+                               ao_wakeup(&ao_stdin_ready);
+#if HAS_SERIAL_SW_FLOW
+                       /* If the fifo is nearly full, turn off RTS and wait
+                        * for it to drain a bunch
+                        */
+                       if (usart->gpio_rts && ao_fifo_mostly(usart->rx_fifo)) {
+                               ao_gpio_set(usart->gpio_rts, usart->pin_rts, usart->pin_rts, 1);
+                               usart->rts = 0;
+                       }
+#endif
+               } else {
+                       usart->reg->cr1 &= ~(1 << STM_USART_CR1_RXNEIE);
+               }
+       }
+}
+
 static void
 ao_usart_isr(struct ao_stm_usart *usart, int stdin)
 {
-       uint32_t        sr;
+       _ao_usart_rx(usart, stdin);
 
-       sr = usart->reg->sr;
-       usart->reg->sr = 0;
+       if (!_ao_usart_tx_start(usart))
+               usart->reg->cr1 &= ~(1<< STM_USART_CR1_TXEIE);
 
-       if (sr & (1 << STM_USART_SR_RXNE)) {
-               char c = usart->reg->dr;
-               if (!ao_fifo_full(usart->rx_fifo))
-                       ao_fifo_insert(usart->rx_fifo, c);
-               ao_wakeup(&usart->rx_fifo);
-               if (stdin)
-                       ao_wakeup(&ao_stdin_ready);
-       }
-       if (sr & (1 << STM_USART_SR_TXE)) {
-               usart->tx_started = 0;
-               if (!_ao_usart_tx_start(usart))
-                       usart->reg->cr1 &= ~(1<< STM_USART_CR1_TXEIE);
-       }
-       if (sr & (1 << STM_USART_SR_TC)) {
+       if (usart->reg->sr & (1 << STM_USART_SR_TC)) {
                usart->tx_running = 0;
                usart->reg->cr1 &= ~(1 << STM_USART_CR1_TCIE);
                if (usart->draining) {
@@ -72,7 +100,7 @@ ao_usart_isr(struct ao_stm_usart *usart, int stdin)
        }
 }
 
-int
+static int
 _ao_usart_pollchar(struct ao_stm_usart *usart)
 {
        int     c;
@@ -82,13 +110,23 @@ _ao_usart_pollchar(struct ao_stm_usart *usart)
        else {
                uint8_t u;
                ao_fifo_remove(usart->rx_fifo,u);
+               if ((usart->reg->cr1 & (1 << STM_USART_CR1_RXNEIE)) == 0) {
+                       if (ao_fifo_barely(usart->rx_fifo))
+                               usart->reg->cr1 |= (1 << STM_USART_CR1_RXNEIE);
+               }
+#if HAS_SERIAL_SW_FLOW
+               /* If we've cleared RTS, check if there's space now and turn it back on */
+               if (usart->gpio_rts && usart->rts == 0 && ao_fifo_barely(usart->rx_fifo)) {
+                       ao_gpio_set(usart->gpio_rts, usart->pin_rts, foo, 0);
+                       usart->rts = 1;
+               }
+#endif
                c = u;
-               ao_usb_putchar(c); ao_usb_flush();
        }
        return c;
 }
 
-char
+static char
 ao_usart_getchar(struct ao_stm_usart *usart)
 {
        int c;
@@ -96,7 +134,6 @@ ao_usart_getchar(struct ao_stm_usart *usart)
        while ((c = _ao_usart_pollchar(usart)) == AO_READ_AGAIN)
                ao_sleep(&usart->rx_fifo);
        ao_arch_release_interrupts();
-       ao_usb_putchar(c); ao_usb_flush();
        return (char) c;
 }
 
@@ -106,10 +143,9 @@ _ao_usart_sleep_for(struct ao_stm_usart *usart, uint16_t timeout)
        return ao_sleep_for(&usart->rx_fifo, timeout);
 }
 
-void
+static void
 ao_usart_putchar(struct ao_stm_usart *usart, char c)
 {
-       ao_usb_putchar(c); ao_usb_flush();
        ao_arch_block_interrupts();
        while (ao_fifo_full(usart->tx_fifo))
                ao_sleep(&usart->tx_fifo);
@@ -149,7 +185,7 @@ static const struct {
        },
 };
 
-void
+static void
 ao_usart_set_speed(struct ao_stm_usart *usart, uint8_t speed)
 {
        if (speed > AO_SERIAL_SPEED_115200)
@@ -157,7 +193,7 @@ ao_usart_set_speed(struct ao_stm_usart *usart, uint8_t speed)
        usart->reg->brr = ao_usart_speeds[speed].brr;
 }
 
-void
+static void
 ao_usart_init(struct ao_stm_usart *usart)
 {
        usart->reg->cr1 = ((0 << STM_USART_CR1_OVER8) |
@@ -203,12 +239,14 @@ ao_usart_init(struct ao_stm_usart *usart)
        ao_usart_set_speed(usart, AO_SERIAL_SPEED_9600);
 }
 
-void
+#if HAS_SERIAL_HW_FLOW
+static void
 ao_usart_set_flow(struct ao_stm_usart *usart)
 {
        usart->reg->cr3 |= ((1 << STM_USART_CR3_CTSE) |
                            (1 << STM_USART_CR3_RTSE));
 }
+#endif
 
 #if HAS_SERIAL_1
 
@@ -296,13 +334,22 @@ ao_serial2_set_speed(uint8_t speed)
        ao_usart_drain(&ao_stm_usart2);
        ao_usart_set_speed(&ao_stm_usart2, speed);
 }
+
+#if HAS_SERIAL_SW_FLOW
+void
+ao_serial2_cts(void)
+{
+       _ao_usart_cts(&ao_stm_usart2);
+}
+#endif
+
 #endif /* HAS_SERIAL_2 */
 
 #if HAS_SERIAL_3
 
 struct ao_stm_usart ao_stm_usart3;
 
-void stm_usart3_isr(void) { ao_usart_isr(&ao_stm_usart3, USE_SERIAL_2_STDIN); }
+void stm_usart3_isr(void) { ao_usart_isr(&ao_stm_usart3, USE_SERIAL_3_STDIN); }
 
 char
 ao_serial3_getchar(void)
@@ -342,6 +389,28 @@ ao_serial3_drain(void)
 }
 #endif /* HAS_SERIAL_3 */
 
+#if HAS_SERIAL_SW_FLOW
+static void
+ao_serial_set_sw_rts_cts(struct ao_stm_usart *usart,
+                        void (*isr)(void),
+                        struct stm_gpio *port_rts,
+                        int pin_rts,
+                        struct stm_gpio *port_cts,
+                        int pin_cts)
+{
+       /* Pull RTS low to note that there's space in the FIFO
+        */
+       ao_enable_output(port_rts, pin_rts, foo, 0);
+       usart->gpio_rts = port_rts;
+       usart->pin_rts = pin_rts;
+       usart->rts = 1;
+
+       ao_exti_setup(port_cts, pin_cts, AO_EXTI_MODE_FALLING|AO_EXTI_PRIORITY_MED, isr);
+       usart->gpio_cts = port_cts;
+       usart->pin_cts = pin_cts;
+}
+#endif
+
 void
 ao_serial_init(void)
 {
@@ -394,10 +463,19 @@ ao_serial_init(void)
 
        stm_afr_set(&stm_gpioa, 2, STM_AFR_AF7);
        stm_afr_set(&stm_gpioa, 3, STM_AFR_AF7);
-#if USE_SERIAL_2_FLOW
+# if USE_SERIAL_2_FLOW
+#  if USE_SERIAL_2_SW_FLOW
+       ao_serial_set_sw_rts_cts(&ao_stm_usart2,
+                                ao_serial2_cts,
+                                SERIAL_2_PORT_RTS,
+                                SERIAL_2_PIN_RTS,
+                                SERIAL_2_PORT_CTS,
+                                SERIAL_2_PIN_CTS);
+#  else
        stm_afr_set(&stm_gpioa, 0, STM_AFR_AF7);
        stm_afr_set(&stm_gpioa, 1, STM_AFR_AF7);
-#endif
+#  endif
+# endif
 #else
 #if SERIAL_2_PD5_PD6
        stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIODEN);
@@ -416,7 +494,7 @@ ao_serial_init(void)
 
        ao_stm_usart2.reg = &stm_usart2;
        ao_usart_init(&ao_stm_usart2);
-#if USE_SERIAL_2_FLOW
+#if USE_SERIAL_2_FLOW && !USE_SERIAL_2_SW_FLOW
        ao_usart_set_flow(&ao_stm_usart2);
 #endif